In the largest study of the genetic analysis of HLH patients, c.50del and c.445G > A in the PRF1 gene and c.143 °C > T and c.1247-1G > C in the STXBP2 gene, known to be frequently reported in HLH patients, were not found in East Asians in gnomAD (32). The gene discussed is PRF1; the disease is hemophagocytic syndrome.